The proposed research will continue an analysis of the properties of the system of cerebral neurons responsive to genital stimulation (genitally-sensitive neurons) in the female cat. Through the use of chronic recording methods, the activity of single-units and unit clusters in the brainstem and diencephalon will be examined during the elicitation of behavioral responses to vaginal stimulation in ovariectomized, anestrous and estrogen-treated cats. The objective is an identification of differences in the activity of these neurons in the estrous and anestrous conditions, and an elucidation of some of the neuronal processes controlling receptivity to genital stimulation in the cat. Quantitative analysis of unit activity under the differing hormonal treatment and behavioral conditions will be conducted in order to establish relationships between estrogen-dependent patterns of unit activity and estrogen-dependent behavioral responses to genital stimulation. Patterns of unit activity which are identified in the chronic recording experiments will be studied further in acute experiments on immobilized animals in order to distinguish estrogen-dependent unit activity which may be causal in the generation of behavioral responses from those patterns of neuronal activity which, in behaving animals, are generated by feedback from movements. The findings from these experiments should contribute to an understanding of the mechanisms through which genital sensations influence the expression of mating behavior and the mode of action of estrogens upon genital sensory processes.